Calcineurin/Nfat signaling is required for perinatal lung maturation and function.
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ABSTRACT:
SUBMITTER: Dave V
PROVIDER: S-EPMC1570374 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Schwann cells develop from multipotent neural crest cells and form myelin sheaths around axons that allow rapid transmission of action potentials. Neuregulin signaling through the ErbB receptor regulates Schwann cell development; however, the downstream pathways are not fully defined. We find that mice lacking calcineurin B1 in the neural crest have defects in Schwann cell differentiation and myelination. Neuregulin addition to Schwann cell precursors initiates an increase in cytoplasmic Ca2+, which activates calcineurin and the downstream transcription factors NFATc3 and c4. Purification of NFAT protein complexes shows that Sox10 is an NFAT nuclear partner and synergizes with NFATc4 to activate Krox20, which regulates genes necessary for myelination. Our studies demonstrate that calcineurin and NFAT are essential for neuregulin and ErbB signaling, neural crest diversification, and differentiation of Schwann cells.
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Project description:In hippocampal neurons, the scaffold protein AKAP79 recruits the phosphatase calcineurin to L-type Ca(2+) channels and couples Ca(2+) influx to activation of calcineurin and of its substrate, the transcription factor NFAT. Here we show that an IAIIIT anchoring site in human AKAP79 binds the same surface of calcineurin as the PxIxIT recognition peptide of NFAT, albeit more strongly. A modest decrease in calcineurin-AKAP affinity due to an altered anchoring sequence is compatible with NFAT activation, whereas a further decrease impairs activation. Counterintuitively, increasing calcineurin-AKAP affinity increases recruitment of calcineurin to the scaffold but impairs NFAT activation; this is probably due to both slower release of active calcineurin from the scaffold and sequestration of active calcineurin by 'decoy' AKAP sites. We propose that calcineurin-AKAP79 scaffolding promotes NFAT signaling by balancing strong recruitment of calcineurin with its efficient release to communicate with NFAT.
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Project description:By studying mice in which the Nfatc1 gene was inactivated in bone marrow, spleen, or germinal center B cells, we show that NFATc1 supports the proliferation and suppresses the activation-induced cell death of splenic B cells upon B cell receptor (BCR) stimulation. BCR triggering leads to expression of NFATc1/?A, a short isoform of NFATc1, in splenic B cells. NFATc1 ablation impaired Ig class switch to IgG3 induced by T cell-independent type II antigens, as well as IgG3(+) plasmablast formation. Mice bearing NFATc1(-/-) B cells harbor twofold more interleukin 10-producing B cells. NFATc1(-/-) B cells suppress the synthesis of interferon-? by T cells in vitro, and these mice exhibit a mild clinical course of experimental autoimmune encephalomyelitis. In large part, the defective functions of NFATc1(-/-) B cells are caused by decreased BCR-induced Ca(2+) flux and calcineurin (Cn) activation. By affecting CD22, Rcan1, CnA, and NFATc1/?A expression, NFATc1 controls the Ca(2+)-dependent Cn-NFAT signaling network and, thereby, the fate of splenic B cells upon BCR stimulation.
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Project description:Pathological cardiac myocyte hypertrophy is thought to be induced by the persistent increases in intracellular Ca(2+) needed to maintain cardiac function when systolic wall stress is increased. Hypertrophic Ca(2+) binds to calmodulin (CaM) and activates the phosphatase calcineurin (Cn) and CaM kinase (CaMK)II. Cn dephosphorylates cytoplasmic NFAT (nuclear factor of activated T cells), inducing its translocation to the nucleus where it activates antiapoptotic and hypertrophic target genes. Cytoplasmic CaMKII regulates Ca(2+) handling proteins but whether or not it is directly involved in hypertrophic and survival signaling is not known.This study explored the hypothesis that cytoplasmic CaMKII reduces NFAT nuclear translocation by inhibiting the phosphatase activity of Cn.Green fluorescent protein-tagged NFATc3 was used to determine the cellular location of NFAT in cultured neonatal rat ventricular myocytes (NRVMs) and adult feline ventricular myocytes. Constitutively active (CaMKII-CA) or dominant negative (CaMKII-DN) mutants of cytoplasmic targeted CaMKII(deltac) were used to activate and inhibit cytoplasmic CaMKII activity. In NRVM CaMKII-DN (48.5+/-3%, P<0.01 versus control) increased, whereas CaMKII-CA decreased (5.9+/-1%, P<0.01 versus control) NFAT nuclear translocation (Control: 12.3+/-1%). Cn inhibitors were used to show that these effects were caused by modulation of Cn activity. Increasing Ca(2+) increased Cn-dependent NFAT translocation (to 71.7+/-7%, P<0.01) and CaMKII-CA reduced this effect (to 17.6+/-4%). CaMKII-CA increased TUNEL and caspase-3 activity (P<0.05). CaMKII directly phosphorylated Cn at Ser197 in CaMKII-CA infected NRVMs and in hypertrophied feline hearts.These data show that activation of cytoplasmic CaMKII inhibits NFAT nuclear translocation by phosphorylation and subsequent inhibition of Cn.
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Project description:The premetastatic niche is a predetermined site of metastases, awaiting the influx of tumor cells. However, the regulation of the angiogenic switch at these sites has not been examined. Here, we demonstrate that the calcineurin and nuclear factor of activated T cells (NFAT) pathway is activated specifically in lung endothelium prior to the detection of tumor cells that preferentially metastasize to the lung. Upregulation of the calcineurin pathway via deletion of its endogenous inhibitor Dscr1 leads to a significant increase in lung metastases due to increased expression of a newly identified NFAT target, Angiopoietin-2 (ANG2). Increased VEGF levels specifically in the lung, and not other organ microenvironments, trigger a threshold of calcineurin-NFAT signaling that transactivates Ang2 in lung endothelium. Further, we demonstrate that overexpression of DSCR1 or the ANG2 receptor, soluble TIE2, prevents the activation of lung endothelium, inhibiting lung metastases in our mouse models. Our studies provide insights into mechanisms underlying angiogenesis in the premetastatic niche and offer targets for lung metastases.
| S-EPMC3763962 | biostudies-literature
Project description:Nuclear factor of activated T cells (NFAT) comprises a family of transcription factors that regulate T cell development, activation and differentiation. NFAT signaling can also mediate granulocyte and DC activation, but it is unknown whether NFAT influences their development from progenitors. Here we report a novel role for calcineurin/NFAT signaling as a negative regulator of myeloid hematopoiesis. Reconstituting lethally-irradiated mice with hematopoietic stem cells expressing an NFAT-inhibitory peptide resulted in enhanced development of the myeloid compartment. Culturing bone marrow cells with Flt3-L and Cyclosporin A, which inhibits NFAT signaling, increased numbers of differentiated DC. Global gene expression analysis of untreated DC and NFAT-inhibited DC revealed differential expression of transcripts that regulate cell cycle and apoptosis. Thus, calcineurin/NFAT signaling negatively regulates myeloid lineage development. The finding that NFAT acts as a negative regulator of myeloid development provides novel insight in understanding immune responses during treatment with calcineurin/NFAT inhibitors as Cyclosporin A. bone marrow cells from C57B/6 mice were stimulated in Flt3-L suplemented media in presence or absence of calcineurin/NFAT inhibitor Cyclosporin A, samples in 3 biological replicates
2011-09-30 | E-GEOD-29094 | biostudies-arrayexpress
Project description:Nuclear factor of activated T cells (NFAT) comprises a family of transcription factors that regulate T cell development, activation and differentiation. NFAT signaling can also mediate granulocyte and DC activation, but it is unknown whether NFAT influences their development from progenitors. Here we report a novel role for calcineurin/NFAT signaling as a negative regulator of myeloid hematopoiesis. Reconstituting lethally-irradiated mice with hematopoietic stem cells expressing an NFAT-inhibitory peptide resulted in enhanced development of the myeloid compartment. Culturing bone marrow cells with Flt3-L and Cyclosporin A, which inhibits NFAT signaling, increased numbers of differentiated DC. Global gene expression analysis of untreated DC and NFAT-inhibited DC revealed differential expression of transcripts that regulate cell cycle and apoptosis. Thus, calcineurin/NFAT signaling negatively regulates myeloid lineage development. The finding that NFAT acts as a negative regulator of myeloid development provides novel insight in understanding immune responses during treatment with calcineurin/NFAT inhibitors as Cyclosporin A.
2011-10-01 | GSE29094 | GEO
Project description:Nuclear factor of activated T cells (NFAT) is a family of transcription factors important for innate and adaptive immune responses. NFAT activation is tightly regulated through the calcineurin/NFAT signaling pathway. There is increasing evidence on non-coding RNAs such as miRNAs playing a crucial role in regulating transcription factors and signaling pathways. However, not much is known about microRNAs (miRNAs) targeting the calcineurin/NFAT signaling pathway involved in immune response in human. In this study, a comprehensive pathway level analysis has been carried out to identify miRNAs regulating the calcineurin/NFAT signaling pathway. Firstly, by incorporating experimental data and computational predictions, 191 unique miRNAs were identified to be targeting the calcineurin/NFAT signaling pathway in humans. Secondly, combining miRNA expression data from activated T cells and computational predictions, 32 miRNAs were observed to be induced by NFAT transcription factors. Finally, 11 miRNAs were identified to be involved in a feedback loop to modulate the calcineurin/NFAT signaling pathway activity. This data demonstrate the potential role of miRNAs as regulators of the calcineurin/NFAT signaling pathway. The present study thus emphasizes the importance of pathway level analysis to identify miRNAs and understands their role in modulating signaling pathways and transcription factor activity.
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Project description:Elevated endogenous cholecystokinin (CCK) release induced by protease inhibitors leads to pancreatic growth. This response has been shown to be mediated by the phosphatase calcineurin, but its downstream effectors are unknown. Here we examined activation of calcineurin-regulated nuclear factor of activated T-cells (NFATs) in isolated acinar cells, as well as in an in vivo model of pancreatic growth. Western blotting of endogenous NFATs and confocal imaging of NFATc1-GFP in pancreatic acini showed that CCK dose-dependently stimulated NFAT translocation from the cytoplasm to the nucleus within 0.5-1 h. This shift in localization correlated with CCK-induced activation of NFAT-driven luciferase reporter and was similar to that induced by a calcium ionophore and constitutively active calcineurin. The effect of CCK was dependent on calcineurin, as these changes were blocked by immunosuppressants FK506 and CsA and by overexpression of the endogenous protein inhibitor CAIN. Parallel NFAT activation took place in vivo. Pancreatic growth was accompanied by an increase in nuclear NFATs and subsequent elevation in expression of NFAT-luciferase in the pancreas, but not in organs unresponsive to CCK. The changes also required calcineurin, as they were blocked by FK506. We conclude that CCK activates NFATs in a calcineurin-dependent manner, both in vitro and in vivo.
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Project description:The timing of lung maturation is controlled precisely by complex genetic and cellular programs. Lung immaturity following preterm birth frequently results in Respiratory Distress Syndrome (RDS) and Broncho-Pulmonary Dysplasia (BPD), which are leading causes of mortality and morbidity in preterm infants. Mechanisms synchronizing gestational length and lung maturation remain to be elucidated. In this study, we designed a genome-wide mRNA expression time-course study from E15.5 to Postnatal Day 0 (PN0) using lung RNAs from C57BL/6J (B6) and A/J mice that differ in gestational length by ?30 hr (B6<A/J). Comprehensive bioinformatics and functional genomics analyses were used to identify key regulators, bioprocesses and transcriptional networks controlling lung maturation. We identified both temporal and strain dependent gene expression patterns during lung maturation. For time dependent changes, cell adhesion, vasculature development, and lipid metabolism/transport were major bioprocesses induced during the saccular stage of lung development at E16.5-E17.5. CEBPA, PPARG, VEGFA, CAV1 and CDH1 were found to be key signaling and transcriptional regulators of these processes. Innate defense/immune responses were induced at later gestational ages (E18.5-20.5), STAT1, AP1, and EGFR being important regulators of these responses. Expression of RNAs associated with the cell cycle and chromatin assembly was repressed during prenatal lung maturation and was regulated by FOXM1, PLK1, chromobox, and high mobility group families of transcription factors. Strain dependent lung mRNA expression differences peaked at E18.5. At this time, mRNAs regulating surfactant and innate immunity were more abundantly expressed in lungs of B6 (short gestation) than in A/J (long gestation) mice, while expression of genes involved in chromatin assembly and histone modification were expressed at lower levels in B6 than in A/J mice. The present study systemically mapped key regulators, bioprocesses, and transcriptional networks controlling lung maturation, providing the basis for new therapeutic strategies to enhance lung function in preterm infants.
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